a(0) = 1; for n>0, a(n) = 2^n + 1.

Terms

a(0) =1a(1) =3a(2) =5a(3) =9a(4) =17a(5) =33a(6) =65a(7) =129a(8) =257a(9) =513a(10) =1025a(11) =2049a(12) =4097a(13) =8193a(14) =16385a(15) =32769a(16) =65537a(17) =131073a(18) =262145a(19) =524289a(20) =1048577a(21) =2097153a(22) =4194305a(23) =8388609a(24) =16777217a(25) =33554433a(26) =67108865a(27) =134217729a(28) =268435457a(29) =536870913